I've created a website using Notepad and Weebly, so I don't have any experience with an off-line website editor, but a quick Google search revealed a lot of products out there, some commercial (Adobe, Microsoft) and some for free.
Although I've never used it, I've heard good things about Kompozer. I'd start with that, personally.
Venii, vidii, vicii
Wii came, Wii saw , Wii conquered